A microscope of the kind referred to above and equipped with a binocular tube is described in U.S. Pat. No. 4,691,997. In this microscope, the adjustment of the ocular to the spacing of the eyes of the viewer takes place in accordance with the Siedentopf principle without a change of the mechanical tube length. The binocular tube is pivoted at the microscope support to vary the viewing elevation; this, however, changes the viewing angle. The optical axis of the microscope support must be adapted to the pivoted optical axis of the binocular tube. A mirror is arranged in the microscope support which is rotatable about a horizontal axis and for this adaptation, the mirror is rotated with the binocular tube through half the angle through which the binocular tube itself is rotated.
A special microscope tube developed especially with respect to ergonomic considerations is described in published German patent application DE-OS 33 05 650. This tube permits the viewing elevation and the viewing angle to be adjusted independently of each other. However, this is performed at the price that three rotatable mirrors must be rotated therewith in correspondence to the adjustment of viewing elevation
U.S. Pat. No. 1,807,613 discloses a microscope tube having three oculars of which two are attached to a base body so as to be rotatable. However, the optical configuration of this tube has a greater complexity than the microscope according to the Siedentopf type.